multinary masteralloys for highly alloyed ti alloys and...

Volker Guether Multinary Masteralloys for Highly Alloyed Ti Alloys and Titanium Aluminides

May 19-21, 2014 • Hilton Sorrento Palace, Sorrento, Italy

AMG TITANIUM ALLOYS & COATINGS

GfE Metalle und Materialien GmbH

Multinary Masteralloys for Highly Alloyed

Ti Alloys and Titanium Aluminides

Volker Guether, Matthias Achtermann (GfE Metalle und Materialien GmbH)

Anke Poetzsch (GfE Fremat GmbH)



Outline

1. AMG Titanium Alloys & Coatings (GfE)

2. Production of master alloys

3. Motivation for multinary master alloys

processing capability

productivity and costs

microstructure and properties

3. Production and properties of AlSnZrMo master alloy

for Ti-6246

4. Summary and outlook



AMG Titanium Alloys & Coatings (GfE)

AMG

Superalloys

AMG

Vanadium

AMG Titanium

Alloys &

Coatings

AMG

Aluminium AMG Antimony

AMG ALD

Vacuum

Technologies

Ferrovanadium Ferronickel-

molybdenum

Tantalum- and Niobium oxide

Chromium metal

Ferrotitanium Metals-based

powders

Aluminium master alloys

Additives

Antimony ore and -trioxide

AMG Processing AMG Engineering

Master alloys for Titanium- and Superalloys

Ti Aluminides Coating materials Vanadium

Chemicals and -Oxides

Metals-based powders

AMG Advanced Metallurgical Group N.V.

(Netherlands)

Vacuum furnace systems

Own & Operate heat treatment facilities

Silicon metal Natural

graphite

AMG Mining

AMG Graphite

& Silicon

AMG

Mineracao

Tantalum ore Niobium ore

3,275 employees

15 countries

4 markets

(energy, aerospace, infrastructure, specialty metals & chemicals)

3 business segments

Revenue 1,216 $m

in 2012

Gross Profit 197 $m

in 2012

EBITDA 85 $m in

2012



Production of master alloys (1)

Basic production route of master alloys via ATR

• raw materials metal oxides and aluminum as well as auxiliary

materials are being mixed/homogenized

• mixture is ignited and reacts exothermally (aluminothermic /

thermite smelting process) within a refractory-lined or

copper vessel

V2O5 + Al

VAl + Al2O3 +

heat



Production of master alloys (2)

Inspection:

- Magnetic separation

- Visual inspection

- Blacklight inspection

- X-ray inspection

- Automatic sampling

- Chemical analysis

- Release by QM

2nd step: VIM alloying / refining

VAl 50:50

Crushing

VIM-Process

Vacuum

Induction

Melting

Sizing

1st step: ATR

V-Oxide Al

Slag

Metal

VAl 65:35

Al Crushing

Alumino-

Thermic Reduction

Process



Motivation (1)

processing capability • Highly alloyed Ti alloys and -TiAl alloys contain substantial amounts of master alloys

Ti-Al6-Sn2-Zr4-Mo6 18 wt.-% -TNM® Ti-43,5Al -4Nb -1Mo -0,1B (at.-%) 20 wt.-% -TNB Ti -45Al -8Nb -2Cr -0,2C (at.-%) 34 wt.-% • The mechanical stability of compacted electrodes (particularly for -TiAl alloys) is being

limited due to substantial powder volumes.

• The processing of granules instead of powders would be preferred but requires the suppression of high melting phases which may be more likely to achieve in a

multinary master alloy system.



Motivation (2)

productivity and costs • addition of one master alloy into a compact instead of partitioning the master alloys into three or even more powders

• cost savings with regard to raw materials e.g. ZrO2 Zr

• save grinding costs and increase materials yields (granules vs. powders)



Motivation (3)

microstructure and properties • binary master alloys of high melting elements with Aluminum such as Nb, Mo or Ta contain high dense / high melting phases in equilibrium conditions the processing of such master alloys as powders is mandatory in order to assure the dissolution / alloying in the final Ti alloy • such high melting phases can be avoided / suppressed by further alloying

with third or fourth elements master alloys can be processed as granules



Motivation (4)

ATR NbAl 70/30

Nb2Al

NbAl3

Formation of extended high melting phases under equilibrium conditions



Motivation (5)

advantage of multinary systems: improve control on phase formation disadvantage: limited number of ternary phase diagrams are available but no quaternary or higher phase diagrams subject to experimental work



AlSnZrMo master alloy for Ti-6246 (1)

Experimental • aluminothermic co-reduction and alloying of

MoO3 ZrO2 Sn

• addition of heat in order to boost the reaction • conditioning of slag system (shift thermodynamic equilibrium conditions) MoO3 + ZrO2 + Sn + KClO4 + slag conditioner + Al Al28 –Sn12 –Zr24 –Mo36 (wt.-%) + slag + heat




chemical analysis in wt.-% ATR alloy specification Al 29,15 27 - 30 Sn 11,90 10 - 13 Zr 22,20 22 -25 Mo 35,65 34 -37 O 0,16 < 0,2 N 0,001 < 0,01 C 0,043 < 0,02




Metallographic investigations: alloy consists of 4 different phases

slag – alloy interface center alloy-bottom interface




Al3Mo(Zr)

Al2(ZrSn(Mo))3

ZrSn

BSE EDX semi-quantitative phase analysis

(MoZr)3Al sporadical with small

sizes




center Al Zr Mo Sn

Al3(Mo,Zr)

element mapping

Al2(ZrSn(Mo))3 SnZr SnZr



Summary

• multinary alloying provides the opportunity to suppress or even prevent the formation of extended high melting phases in master alloys

• this is an important pre-condition to process granules instead of powders in order to improve the VAR consumable electrode stability particularly for highly alloyed Ti alloys and Titanium Aluminides • GfE has developed and successfully introduced multinary master alloys for the production of Ti-17, Ti-6246, TiAl TNM, TiAl 48-2-2 and others



Thank you for your attention!

GfE‘s team during the 100 year anniversary in 2011

multinary masteralloys for highly alloyed ti alloys and...

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